The invention relates to a recording and/or reproducing apparatus tape which can be driven selectively in one of two directions of transport between two rotatable winding hubs. Two rotatable winding spindles for driving the two winding hubs are coaxially mounted on the spindles and take up the tape in conformity with the selected direction of transport. A drive mechanism for driving the winding spindles has a first drive wheel which can be rotated in one of the two directions of rotation by a motor and a second drive wheel which is rotatable relative to and coaxial with the first drive wheel. The second drive wheel can be rotated by the first drive wheel via a coupling device comprising two friction couplings to drive one of the two winding spindles depending on its direction of rotation.
Such an apparatus is disclosed in EP-A-No. 0,079,053 to which U.S. Pat. No. 4,499,512 corresponds. In this known apparatus each of the two friction couplings, which are constructed as felt-disc couplings, always cooperate with a radial surface of the first drive wheel, one of the two friction couplings always cooperating with a radial surface of the second drive wheel and the other friction coupling always cooperating with a radial surface of a spring-loaded pressure disc which is fixed to the second drive wheel. In both directions of rotation of the first drive wheel the two friction couplings therefore always operate simultaneously and parallel. The provision of two friction couplings operating with parallel forces ensures that a comparatively large torque can be transmitted with a comparatively smooth coupling characteristic. However, as the two friction couplings operate simultaneously for both directions of rotation they are only capable of transmitting one specific torque to the second drive wheel and hence to the two winding spindles for both directions of rotation.
However, it is often required to drive the two winding spindles with different torques in order to compensate for the different friction effects of the guide means and scanning elements on the record carrier and the resulting difference in tape tension when the record carrier is wound onto the two winding hubs in each of its two possible directions of transport. For this purpose each winding spindle may be driven via a separate coupling device comprising at least one friction coupling, enabling different torques to be transmitted by means of these two separate coupling devices. However, the use of separate coupling devices is unfavourable in view of costs and the required space.